Checklists for Complicated Details Can Help Ensure Top-Notch Installations

Our clients are asking for sustainable, durable, robust, long-term roofing systems. In order to achieve these goals, every facet of the project must be well detailed — so much so that many of the details required to achieve our clients’ goals have become very complex. Details often involve multiple trades, requiring coordination and study prior to construction.

Photo 1: The new roof drain has been located and the sump pan provided by the roof drain manufacturer has been installed. IMAGES: HUTCHINSON DESIGN GROUP LTD.

As our details increased in complexity, the work crews — who never seem to have the full-sized drawings on the roof, but reduced copies with the text too small to read — had difficulty understanding the details and comprehending the coordination required to achieve the design intent. If I were in the field, I would often sit with the foreman and review the details, challenging them to understand “looking ahead” and to be sure all the materials were on-site. You all know how it works — the foreman says the superintendent has that, the same superintendent that doesn’t own a note pad and seldom looks at the drawings. Not to digress too far, but when we started having young roof consultants, some RROs observed re-roofing construction in the field, and they sometimes didn’t quite understand the detail as well as they should have, resulting in work having to be corrected.

Photo 2: In this replacement roof drain, the underdeck clamp and drain bowl insulation have been installed. It is amazing how many roof drains do not have an underdeck clamp and are pulled out of the roof deck in a wind event.

Thinking about how to educate my staff and help them understand the detail intent and the installation process required, I came upon the idea of creating a step-by-step installation checklist of all the components of a detail that they could use to observe the construction. We started with the installation of a new roof drain, a detail that was of particular concern. The list assisted not only the consultants, but also the roofing crews in the field. Thus, we followed this up with additional installation progressive checklists for most of the challenging components of a roof system: roof edge, pipe penetrations, flue penetrations, roof drains, and so forth. These worked so well that we started sharing these lists with the roofing, plumbing and HVAC contractors. We decided to call them “Quality Assurance Compliance.”

The Roof Drain Checklist

The roof drain is where the water goes — or at least where it is supposed to go. As insulation thicknesses increase by code, air and vapor retarders became more prevalent, and air transport into the roof systems not desirable, our roof drain details have become increasingly complex. For an example, see Figure 1, New Roof Drain Detail: Lead Joint.

Photo 3: This new roof drain has had its underdeck clamp installed. The underdeck clamp secures the drain to the deck so that it cannot move.

The process of preparing the quality assurance compliance list began with me meeting with the observer, explaining the goal, and asking them to review and study a particular detail, typing out a list of requirements and placing them in order from start to finish. I then reviewed the list and met again with the observer to discuss it. When the list was 99% complete, I reviewed the list with the contractors that would be involved with the detail for their input, concerns and issues. For our example, the roof drain, this would involve review and discussion with the plumbing and roofing contractors, both on the same call so both could hear and understand the other’s needs.

Photo 4: The modified bitumen vapor retarder has been taken over the drain flange of at this newly installed replacement roof drain. The reversible collar for the threaded extension ring has been placed and secured.
Photo 5: The self-adhering vapor retarder has been taken over the drain flange at this newly installed replacement roof drain. The reversible collar for the threaded extension ring has been placed and secured.
Photo 6: The perimeter of the roof drain has been sealed with spray foam insulation. After setting, it will be trimmed back prior to the membrane application.
Photo 7: The roof insulation and cover board have been installed. The drain extension ring has been set to the underside of the cover board and the cover board cut vertically.
Photo 8: A full tube of water block should be placed on the extension ring flange. Note the perfectly cut cover board.
Photo 9: This is not acceptable membrane cutout at the drain.
Photo 10: A well-done drain installation. The membrane has been cut in a cloverleaf pattern to the drain extension ring, the clamping ring is set, and the drainage slots are below the surface of the roof. Note: If the brush doesn’t go into the drainpipe, we’ll be good.
Figure 1: New Roof Drain Detail: Lead Joint

The Drain Quality Assurance Compliance Checklist is included below.

New Roof/Existing Roof:

Drain Quality Assurance Compliance

1. Has interior protection been installed?

 Yes   No

2. Coordinate the work of this detail with the plumbing contractor?

 Yes   No

3. a. Has the new roof drain location been properly determined?

 Yes   No

b. Has the drain location been confirmed with the architect and owner?

 Yes   No

4. a. Has the existing the steel roof deck been cut out to accommodate just the sump pan?

 Yes   No

b. Have the new interior steel framing angles been installed?

 Yes   No

5. Has the roof drain sump pan (provided by roof drain manufacturer) been correctly installed level and fastened tight to the deck? (See Photo 1.)

 Yes   No

6. Has the new cast iron roof drain been installed, caulk joint to downspout properly installed? Has the under deck clamp been installed? (See Photos 2 and 3.)

 Yes   No

7. Does the vapor retarder extend onto the drain flange? (See Photos 4 and 5.)

 Yes   No

8. Is the reversible rain collar installed compressing the water cut-off mastic below the vapor retarder?

 Yes   No

9. Has water cut-off mastic been placed on the extension ring threads prior to engaging with the reversible collar?

 Yes   No

10. Is the base layer and tapered insulation cut to fit below extension ring?

 Yes   No

11. Has the extension ring been set so that the clamping ring is 1/2 inch below the top surface of the coverboard?

 Yes   No

12. Is the space between the insulation and roof drain filled with spray foam insulation? (See Photo 6.)

 Yes   No

13. Is the cover board cut vertically (not sloped) flush with the clamping ring flange edge? (See Photo 7.)

 Yes   No

14. Has a 1/2-inch diameter bead of water cut-off mastic been installed continuously atop the extension ring flange, below the single-ply roof cover at the clamping ring location? (See Photo 8.)

 Yes   No

15. Has the clamping ring been set and have all the clamping ring bolts been tightened?

 Yes  o No

16. Has the single-ply roof cover been cut to within 1/2 inch to the clamping ring in a cloverleaf configuration around the clamping bolts? (See Photos 9 and 10.)

 Yes   No

17. Has the cast iron drain dome been installed and locked into the clamping ring? (See Photo 11.)

 Yes  No

18. Has the drain bowl insulation been installed over the roof drain and sump pan?

 Yes   No

19. Has the drainpipe been installed?

 Yes   No

Closing Thoughts

We have used these quality assurance compliance lists for several years, modifying them as empirical experience suggested. We have found them to be a great educational tool for both the observers and the construction crews. An additional benefit, that I didn’t see coming, was new draftsmen, unfamiliar with either roof or the complexity of the details, have found that these lists helped them understand how the detail would go together and thus have improved the quality of their work.

Achieving our clients’ goals has to be our passion. Designing and installing solid, resilient details is how we do so. I am all in for improving in-field construction and have found that many field service crews have great ideas. Quality Assurance Compliance is one way we have incorporated those ideas feel, and we believe it has brought and will bring better workmanship and long-term service life to our life’s blood — our clients.

Next: Raising the plumbing vent.

About the author: Thomas W. Hutchinson, AIA, CSI, Fellow-IIBEC, RRC, is a principal of Hutchinson Design Group Ltd. in Barrington, Illinois. For more information about the company, visit

About the Author

Thomas W. Hutchinson, AIA, CSI, Fellow-IIBEC, RRC
Thomas W. Hutchinson, AIA, CSI, Fellow-IIBEC, RRC, is principal of Hutchinson Design Group Ltd., Barrington, Ill., and a member of Roofing’s editorial advisory board.

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